An equation is like a balance scale because it shows that two quantities are equal. Look at the scales and equations below. The scales remain balanced when the same weight is added to each side.
balance equations on a scale
Similarly, the scales remain balanced when the same weight is taken away from each side. This demonstrates the addition and subtraction properties of equality.
Solving One-Step Equations
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What You'll Learn
[[http://www.phschool.com/iText/math/sample_chapter/Ch02/02-01/PH_Alg1_ch02-01_Obj1_voc3.html|]]Solving Equations Using Addition and Subtraction
An equation is like a balance scale because it shows that two quantities are equal. Look at the scales and equations below. The scales remain balanced when the same weight is added to each side.